package/ofono: bump to version 1.31

Bugfix release. From the ChangeLog:

Ver 1.31:
 - Fix issue with handling CID 0 context identifier.
 - Fix issue with handling detach state and running LTE.
 - Fix issue with handling SIM states and Quectel modems.

Signed-off-by: Anthony Viallard <viallard@syscom-instruments.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>